Abstract

Field emission characteristics of sol-gel (Ba0.67Sr0.33)TiO3 (BST) ferroelectric thin film coated silicon emitters have been systemically investigated. The effects of BST coating, BST annealing temperature, and biasing at BST-silicon junction on field emission characteristics of BST coated silicon tips have been studied. The authors have found that field emission characteristics of silicon tips can be significantly improved by BST coating. The turn-on electric field required between the silicon tips and the anode significantly reduced from 70 to 4–20 V/µm by BST coating. The theoretical studies have shown that the improved emission characteristics by BST coating may be attributed to the lower electron affinity and the lower work function properties of BST material. Emission stability was also improved by BST coating. BST coated silicon emitter has a relatively stable emission current with 20% fluctuation compared to 50% current fluctuation of uncoated silicon tips. It was also found that the emission characteristics of BST coated silicon tips strongly depended on BST annealing temperature. The samples with 750 °C BST annealing temperature were found to have the best emission characteristics with low turn-on electric field of 4–9 V/µm. A higher annealing temperature results in higher activation of ionic conduction, increasing carrier concentration, raising the Fermi level toward the conduction band, and thus reducing the effective work function. Finally, the electron field emission from BST coated silicon tips was improved significantly by the positive bias on BST-silicon junction. The theoretical studies have shown that the effective work function is reduced with a positive bias on BST-silicon junction and hence the turn-on electric field is significantly reduced by the bias on BST-silicon junction